Ecology:


The big picture: Earth’s climate controls species distributions




  • Ecology can be measured at many different levels
    • individual → ecosystem → biosphere


  • The environment regulates where species can be
    • What regulates the environment?


  • Earth is divided up into different life zones
    • control the distribution of species
    • climate creates life zones


  • Abiotic and biotic factors determine where species can exist

What is climate?





  • Climate:
    • i.e. temperature, precipitation, sunlight & wind
    • often 30 year averages



  • Global climate depends on the amount of energy received by the sun and the amount of energy that is trapped in the system.
    • Different regions can have different climates.

What is climate?


  • Requires measurements of weather conditions at thousands of locations every day of the year
    • observations used to quantify long-term average conditions

Climate varies by latitude



  • Solar energy (sun) warms the air, land & water
    • impacts temperature
    • impacts air movement (wind patterns)
    • impacts evaporation


  • Earth is round, sun radiation strikes unevenly
    • direct @ equator
    • more diffuse (spread out) towards poles


  • Creates differences in climate across latitudes
    • relation north or south of the Earth’s equator

Climate varies by season



  • Earth is titled & spinning as it circles sun
    • impacts day length
    • impacts amount of solar energy
    • impacts temperature


  • Climate within a latitude change during the year
    • dry & wet seasons
    • wind and ocean currents


  • Seasonal variation smallest at equator
    • increases towards poles

Climate varies by latitude


Bodies of water play huge role in climate






  • Oceans are heat conveyor belts
    • heat/cool air masses
    • currents move them



  • Impacts climate of land
    • water absorbs lot of heat!

Climate patterns distribute life on Earth



  • Major zones of vegetation are called biomes
    • tropics → desert → tundra


  • Biomes are largely defined by temperature and precipitation
    • annual averages
    • seasonal variation


  • Why do areas of N. America, with similar annual averages of climate factors, support either deciduous trees or evergreen trees?

Distribution of terrestrial biomes


What makes a biome a biome?


  • Biomes named for:
  1. Physical features (polar ice)
  2. Climate features (tropical / temperate)
  3. Vegetation (grassland / broad-leaf forest)
  • Contain organisms adapted for the environment
    • animals, plants, fungi, etc


  • Boundaries between biomes are not firm
    • ecotones: areas of overlap

What makes a biome a biome?




  • Biomes are divided into vertical layers
    • aboveground & belowground
    • each layer has distinct species


  • Species composition varies within biomes
    • abundance or presence/absence


  • Question: Why will different desserts have similar looking but unrelated species of cacti?

Aquatic biomes are also diverse



  • Characterized by physical and chemical environment
    • fresh vs saltwater
    • depth of light penetration


  • Oceans cover 3/4 of Earth’s surface
    • evaporation fuels rainfall
    • algae and bacteria supply O2
    • regulate global temperature and wind


  • Freshwater biomes linked to terrestrial neighbor
    • soil inputs determine chemistry
    • related climate

Species distributions: Where and Why?





  • Species distributions are part ecology & part evolution


  • Why are kangaroos only in Australia?


  • Why are different kangaroos in some habitats but not others?
    • abiotic factors?
    • biotic factors?

Kangaroos evolved in Australia


Dispersal keeps kangaroos in Australia (mostly)



  • Dispersal:
    • limits the distribution of a species


  • Some organisms can disperse widely
    • which ones?
    • Kangaroos cannot
    • humans are unnatural dispersers


  • Geographic isolation is key to evolution

Kangaroo species are adapted to climate


Abiotic limitations to Red Kangaroo distribution


Biotic limitations to kangaroo distribution (competition)


Where can a species exist?